1. Field of the Invention
The invention relates to an interactive speech interface unit for operating applications using an interactive speech.
2. Description of the Related Art
A speech interface unit for operating applications by speech has been recently devised. FIG. 22 shows an example of the operation of an application using a conventional interactive speech. Although an actual input by a user and a response by a system are performed by a sound or speech, a statement comprised of the mixture of kanji and kana is used hereafter for the convenience of an explanation.
In the interactive speech, flow of dialog need be controlled so as to perform the dialog smoothly. The flow of dialog means a manner of response by a system to the input by a user wherein when a system performs appropriate responses, an efficient interactive speech function can be realized.
An interactive sequence means data which the system holds therein for the purpose of controlling the flow of dialog. The interactive sequence is a network describing statuses of the system in the dialog, an event (results of analysis of a user utterance, results of data, statuses of various flags), an action for operating something (feedback from the system to a user, application operations, setting of various flags) and a next transitive status.
FIG. 23 is an example of a conventional interactive sequence (an interactive sequence as disclosed in a second reference, described later). Characters encircled by squares represent statuses. When an event occurs at every interactive status, an action to be executed by a system relative to the event occurred and a status to be transitive after execution of the action are described. The interactive sequence is first started from an initial status and ended when it transits to an end status. Further, with the interactive sequence, in some status, that status is once stored and another interactive sequence is executed, then an operation can be restarted from the stored status of a source interactive sequence upon termination of the interactive sequence like a subroutine call in a program language.
In this case, an execution extending from a starting status to an ending status of the interactive sequence corresponding to the subroutine call becomes one action of the source interactive sequence.
The method of controlling flow of dialog is changed depending on an application operated by interactive speech and a field which the application handles. There are following references relating to an invention for facilitating easiness of conversion (hereinafter referred to as field conversion property) when the application or the field is changed.    First Reference: Japanese Patent Laid-Open Publication No. 8-77274    Second Reference: Japanese Patent Laid-Open Publication No. 11-149297
In the first reference, a module referred to as “interactive sequence switching part” selects a corresponding one interactive sequence pattern from interactive sequence patterns stored in an interactive sequence storage part in response to kinds of service which is selected by a user. A field conversion property is enhanced by replacing an interactive sequence pattern to be stored in the interactive sequence storage part.
In the second reference, an interactive sequence is divided into two layers of interactive sequences wherein an upper layer is for a general part and a lower layer is for a field dependent part, and wherein the lower layer interactive sequence is subjected to a subroutine call from the upper layer interactive sequence. When the lower layer interactive sequence is replaced by another interactive sequence, the field conversion property is enhanced.
However, in the technique as disclosed in the first reference, interactive sequences are replaceable as a whole at every field, application so that the efficiency of the preparation of the interactive sequence is not achieved. As a result, it has been necessary to develop interactive sequences at every corresponding applications and fields.
Further, although the field conversion property is enhanced by re-preparing only the lower layer interactive sequences in the invention as disclosed in the second reference, there is a possibility that the modification of the lower layer affects the upper layer, and hence the field conversion property is not always sufficient.
Still further, in either reference, there is no means for a user to customize a flow of dialog.